How an Amp Tech Fixes Fender Deluxe Reverb Squeal


The Fender Deluxe Reverb is a legendary guitar amplifier, adored for its warm, clean tones and rich reverb. It has been a staple in our studio for years but we know it doesn’t come without issues. The most commonly reported issue with this wonderful amp is a squealing noise, with most players not being sure of the source. Could it be the tubes? Could it be the reverb? Well it gets a little more complicated than that. This is why I created this guide. I asked one of my colleagues Sebastian, who is an experienced amp tech to walk us through how he would troubleshoot this issue and resolve it himself. So lets dive in and see how an actual expert would fix reports of a Fender Deluxe Reverb squeal.

An Amp Tech Fixes a Fender Deluxe Reverb

Sebastian will walk us through troubleshooting the squealing issue from his perspective and in great detail. I hope that you find his description of how he goes about fixing this problem to help you understand how to fix your own amp without having to take it in to a tech. But keep in mind, sometimes you just have to get that expert touch with your amp since the issue might be deeper than you first anticipated. Lets dive in!

Help, My Fender Deluxe Reverb Is Squealing!

I’ve seen this problem quite often. I think its because of how popular the Deluxe Reverb has become and somewhat of a quality decline on these amps. The way it usually goes is a customer walks in complaining of a squealing sound coming from their amp. In the most recent case I remember, the customer kept saying he thought it was the reverb causing the issue, but wasn’t sure. I took note of this but still went through my usual routine with a checkup on a new walk-in amp. These are my usual steps.

Verify the Issue

First, I verify that I can reproduce the squealing the customer mentioned. I grab a cable, plug in a guitar, turn the amp on and see what I find. Unfortunately, I hear the squealing, so, we’ve got fixing to do. First the often overlooked step, the cable check. I swap cables, try a different guitar with different pickups to see if the issue persists, sadly it does. We know the squealing is there, and the guitar and the cables are not the cause of the issue. The easy part is done and now we have to dig deeper.

First Suspect: Reverb Tank

Since the customer mentioned that they thought the reverb was somehow involved in the squealing, I want to examine the reverb tank for any issues first. If the reverb tank is not mounted securely or is in contact with other components, it can pick up and amplify unwanted vibrations. I make sure that nothing was touching the reverb tank, if its loose I tighten it. If the noise disappears, it’s likely that the issue was a loose or misaligned reverb tank. If it still persists, I have to dig deeper by removing the reverb tank.

I open the tank and inspect the springs, the input and output transducers, and the cables connecting them to the amp. The key is to look for any signs of damage or loose connections. Here we wont get far without using a multimeter – if you plan on working with amps you need this tool – to test the resistance of the input and output transducers. If the readings are not within the specified range for the amp, it’s likely that one or both of the transducers are faulty and need to be replaced. If a faulty transducer is identified, I would replace it with a new one.

It’s also possible that the reverb driver tube is causing the squealing issue. In that case, I would replace the tube with a new one to see if that solves the problem. I would then reconnect the tank to the amp and test it to see if the issue is resolved. If there is no more squealing, great we fixed the problem.

Usual Suspect: Preamp Tubes

What if the customer never mentioned the reverb tank? I would probably think tubes first, as faulty tubes commonly cause squealing noises. Tubes tend to become what we call microphonic, where they start to pick up noise off the speaker in the amp. The Fender Deluxe Reverb comes with 3 types of tubes. The preamp tubes are generally more susceptible to becoming microphonic than power tubes or rectifier tubes that are present in the amp. This is because preamp tubes are typically more sensitive and handle a wider range of frequencies, which can cause them to pick up more vibration and become microphonic over time.

That being said, any tube in the amp has the potential to become microphonic, and it’s important to test each one individually to isolate the issue.To test for this I gently tap each tube with a pencil while the amp is turned on and the volume is turned up. If I hear any loud, ringing noises coming from the amp, it’s likely that the corresponding tube is microphonic and should be replaced. In general when inspecting the tubes, I would look for any signs of damage, such as cracks or discoloration, and replace any damaged or microphonic tubes with new ones.

Grounding and Circuitry

While I’m already looking around in the amp. I will make sure that the amp’s grounding is set up correctly. I’m looking for the ground wire and checking that it’s properly connected to the amp’s chassis and not loose or broken. If I suspect a grounding issue, I will also make sure to test the amp on another power outlet as well to make sure the problem is resolved.

Before closing up the amp to test it again, I do a quick run down of the general circuitry. I check for damage, loose connections, or anything else that can be the cause of the noise, if anything is broken I fix or replace as needed (keep in mind this might require soldering). We’re now ready for the final steps! Ive checked the reverb tank, and all the tubes and circuitry. Everything damaged has been replaced. Time to test the amp!

Testing and More Testing

I plug in the last guitar and cable I used on the amp and test again. ‘Lo and behold the squealing noise is gone. The amp sounds fresh and crisp. Make sure if you are ordering tube replacements consult Fender for specifics on their Deluxe Reverb amp to get the correct pairing. Remember that each generation of this amp (Blackface, Silverface, Reissue, etc) all have a different tube configurations. You will cause more harm than good if you do something wrong when it comes to tube pairings.

Expert Warning

In general, keep in mind you’re working with electronics, powerful ones at that. If you aren’t sure what you are doing, its best to bring your amp to a technician like myself. Last thing you want to do is cause irreparable damage to your amp in the process of fixing it. That being said, I’ve seen this issue quite often and a lot of the time fixing it is simply replacing or or more of the now microphonic pre-amp tubes, and the squealing is gone.

We will include a list of tubes that Sebastian was referring to below. It’s worth noting that there may be some variation in the tube complement depending on the specific year or model of the Deluxe Reverb. Additionally, some players may choose to modify their amp’s tube complement to achieve different tones or performance characteristics. You have to do your own exploring to figure out which tones best suit your needs.

What Tubes Do Fender Deluxe Reverb Amp Use?

Each era of the Fender Deluxe Reverb had its own set of tubes that were commonly used. However, there may have been some variation between individual amps. Here is a general overview of the tube complement for each era:

  • 1963-1967 (Blackface era): These amps typically used a 5AR4/GZ34 rectifier tube, two 6V6 power tubes, and four 12AX7 preamp tubes.
  • 1968-1981 (Silverface era): These amps typically used a solid-state rectifier, two 6V6 power tubes, and four 12AX7 preamp tubes. Some models from this era may have used 6L6 power tubes instead of 6V6 tubes.
  • 1982-1986 (Blackface Reissue era): These amps were built to the same specifications as the original 1960s Blackface amps.
  • 1987-present (Vintage Reissue era): Same as above.

Final Thoughts: Fender Deluxe Reverb Squeal

This brings the guide to a close. If your Fender Deluxe Reverb amp is squealing, I hope that following the steps outlined by our expert amp technician helps you troubleshoot your own amp. If the issue is not as easy to resolve I would highly recommend taking your beloved amp in for a visit with the amp doctor. Some of the issues might be beyond your repair capabilities, and the last thing you want to happen is having you hurt the amp or yourself in the process of fixing it. I hope you found this article helpful and thank you for reading.

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